Introduction: The development of new drugs for cancer therapy or diagnosis can be a challenge when taking into account several factors like efficacy, clinical safety, toxicity and formulation [1]. Particularly, in stomach diseases such as gastric cancer the testing of new drug delivery systems for diagnosis or therapy can still be aggravated by high variability and the lack of a reliable cellularized model that closely replicates the stomach mucosa. The development of an artificial in vitro tissue engineered model for mimicking the gastric mucosa would provide a solution to this problem improving the field of stomach-directed drug development.
Current approaches to model the gastric mucosa rely merely on isolated gastric epithelial cells, usually comprising just one cell type, which does not accurately mimic the architecture and cellular response within the stomach [2]. In contrast, three dimensional (3D) culture models enclose a great potential to build up a bridge between cell culture models and in vivo animal models [3].
The present study establishes a complex and innovative cell-based 3D model of the gastric mucosa, extending an established gastric monolayer model to the deeper layers of the stomach, in particular the gastric mucosa that includes a wide variety of stromal cells. The designed model intends to explore the epithelial stromal interactions in the gastric mucosa and evaluate its functionality and integrity through permeability studies.
Materials and Methods: The developed model comprises a gastric stromal cell line (NST-20 normal stomach fibroblasts) embedded in a 3D alginate-RGD hydrogel prepared on the basolateral side of a transwell insert, mimicking the extracellular matrix and cellular component of the gastric mucosa, onto which a moderately differentiated adenocarcinoma stomach epithelial cell line (MKN28) was seeded facing the apical compartment, capable of reproducing the physiological conditions of the gastric barrier.
Results and Discussion: Comparing to the monolayer model, this new 3D model more closely resembles the native structure of the gastric mucosa, in which stromal cells showed to have a role in the establishment of mucosal architecture, confirmed by the production of extracellular matrix.
The transport of a fluorescent paracellular marker and commercially available nanoparticles through the gastric model was modulated by the presence of fibroblasts within the hydrogel and the tight character of epithelial cells that mimic the varied populations along the gastric mucosa.
Conclusions: Overall, the 3D model herein presented constitutes a step forward in the development of a more accurate in vitro model system of the stomach, which has the potential to be routinely adopted as a platform for high-throughput evaluation of innovative therapeutics and diagnosis of gastric diseases.
This work was financed by Portuguese funds through FCT – Fundação para a Ciência e a Tecnologia in the framework of project UID/BIM/04293/2013. BN Lourenço and T dos Santos gratefully acknowledge FCT for a doctoral grant (SFRH/BD/87400/2012) and a post-doctoral grant (SFRH/BPD/ 103113/2014), respectively
References:
[1] Sarmento, B., et al. (2012). "Cell-based in vitro models for predicting drug permeability." Expert opinion on drug metabolism & toxicology 8(5): 607-621.
[2] dos Santos, T., et al. (2015). Cell-based in vitro models for gastric permeability studies, in Concepts and models for drug permeability studies – Cell and tissue-based in vitro culture models. Concepts and models for drug permeability studies – Cell and tissue-based in vitro culture models. Elsevier.
[3] Pampaloni, F., et al. (2007). "The third dimension bridges the gap between cell culture and live tissue." Nature reviews Molecular cell biology 8(10): 839-845.